Former FBI agent Bob Levinson disappeared in Iran more than eight years ago.

Dan Levinson, his son, and Naghmeh Abedini, the wife of Saeed Abedini, spoke to Greta Van Susteren tonight, saying that it's time to bring their family members home.

Levinson and Abedini said that they both won't stop fighting until they are released.

Van Susteren asked them how painful this situation has been.

"Every day is like a nightmare," Levinson replied. "It's just so hard for us ... especially the longer it drags on. The depression of just knowing how he's suffering much worse than we are and all he wants to do is get back home to his family and everyone he knows and loves."

Abedini added that it gets harder as the years go by. She said that these few weeks are "very crucial" to make sure that no Americans are left behind in Iran before a nuclear deal is signed.

"During these nuclear negotiations ... this is crunch time, because there's only a few weeks left whether a deal happens or not," Levinson added. "This is a time that our governments are talking and engaged and this is the chance they both have to bring people home."

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